How do YOU determine EI?greenspun.com : LUSENET : B&W Photo - Film & Processing : One Thread
I'm sure many of you have personal EI's for film/developer combinations.
How, exactly, did you arrive at these times?
If left to my own devices, I would simply set up a well-lit kodak reference card (with a full grey scale), a grey card in the same position for a meter reading (removed to expose the ref. card) with the film and filter I plan on using. I would make many exposures in increments, repeating for a few rolls, each being processed for more and less time than recommended, and of course, one at the recommended time. I would find the nicest neg on each roll, and compare those 3-5 negs by printing and whichever roll (time) gave the best range of tones would be it! The other rolls would give me an idea of EI's for higher and lower contrast scenes.
Or is this too complicated? Any easier ways?
I don't want textbook answers, just your experience.
Thanks immensely in advance-
-- Mike DeVoue (email@example.com), February 15, 2002
Prior to now, I'd sneak up on it. I keep a notebook in the darkroom and record negative appearance and how it printed (grade of paper). I'd adjust the EI and development time, and continue the feedback process. After a few rolls, everything falls into place. Recently I decided to get a bit more scientific and did a series of exposures with a white diffuser in front of the lens. Measured the density of each frame. Plotted the curves and did the 0.1 over base plus fog thing. Matched the density range to Kodak and Ansel's suggestions for paper grade. The two methods gave pretty much the same result. I might add that once you've seen 0.1 over b+f a few times, you can do it by eye. No densitometer required unless you want the rest of the curve!
-- Conrad Hoffman (firstname.lastname@example.org), February 15, 2002.
How I do it is wrong. The RIGHT way is easiest described in Fred Picker's book: "The Zone VI Workshop". He describes in detail the correct way to find a personal EI, developing time etc etc.
-- RICHARD ILOMAKI (email@example.com), February 16, 2002.
Sorry Mike, my experience *is* a textbook answer. Followed the procedures outlined in Adams' "The Negative." Only necessary once per film/developer combination. Then go shoot!
-- Sal Santamaura (firstname.lastname@example.org), February 16, 2002.
I have a densitometer but I tend to go about finding EIs backwards. I'll usually shoot a few rolls of a film I'm unfamiliar with and tweak my EI and development times until I get something I'm happy with and then confirm it with a Zone I and Zone VIII exposure on the densitometer.
That way I feel at least I'm shooting stuff rather than gray targets to get to my EI.
I also shoot a Zone I and Zone VIII target at the begining of a roll every now and than just to confirm my EI and times.
-- David Parmet (email@example.com), February 16, 2002.
I had a photo teacher that always told his students to take the original EI and cut it in half. Of course that works for some people, but I used "The Negative" and a densitometer. Another thing people do is to shoot a roll of film, or in my case 2 or 3 sheets of film. Shoot with the original EI and then the same with the next slower speed and then the next slower speed. (ex: 100, 80, 64) Then I just picked which one appealed to me. Magically, it was the same speed I had gotten from the textbook procedures. Happy shooting!
-- Mark Wiens (firstname.lastname@example.org), February 16, 2002.
I use to expose grey cards and then have someone plot the results with a densitometer. Now I simply expose a couple different subjects that are close to home or use a simple set up with a grey card, new white and black lace blouses or cotton shirts. Expose three sets of negs, 1/2 stop difference 3 stops each side of mfg ASA using my spot meter to determine initial exposure. One set gets normal development, one + and one -. I do this for any new film, developer (if I intend to use it extensively), shutter/lens for LF or camera body for 35mm.
When i first did this I would make 5x7 prints of each roll and then paste them to a poster board as a kind of ring around matrix to help me better understand relationships between exposure and development time with regards to final negative densities. A teacher I had in college suggested this and I think it is an excellent exersice for beginners in the darkroom.
Now I can pretty much determine my results with the negs on a light table and just a couple of prints to verify the look I want.
-- James Chinn (JChinn2@dellepro.com), February 16, 2002.
I use a grey card and fill the frame giving it different exposures with a wide range separated by 1/2 stop. You need around 10 or so negatives to do this. The one poster is correct in that after awhile you can spot a zone 1 negative (0.1) without a densitometer. The next part is a little tricky and there you need a densitometer: you have to find the zone VIII negative. I target a density of 1.05 - 1.15, which I am not sure is correct... The zone VIII negative will determine your development time. I guess I am still in a learning curve.
FWIW, I read a good post once on this board that someone just used a light meter to view the negatives on a light box and then measured the EV difference between the difference negatives as a way to make a cheap densitometer. I may try this next time to see how accurate this method is.
-- Russell Brooks (email@example.com), February 18, 2002.
There is an easy to understand discussion on determining EI contained The Kodak Workshop Series book Titled Advanced Black & White Photography. I have used these instructions for about 4 years with excellent results. The chapter in particular is called Controlling your system.
-- Robert Orofino (firstname.lastname@example.org), February 18, 2002.
The problem with shooting a grey card full frame is that it negates the effect of lens flare. It doesn't take a bright object or light source outside the frame to cause flare. It's best to adjust exposure using "real world" subjects and conditions. I once had a teleconvertor that had enought flare to reduce exposure 1 stop from what would be expected. Shadow density was increased but shadow contrast was decreased.
-- Tim Brown (email@example.com), February 19, 2002.
I just take a bunch of pictures of the kinds of things that I usually shoot, exposing at plus/minus one stop from the rated ISO at 1/3 stop intervals. Look at the negatives to see which has the minimun acceptable shadow detail. And then use that EI. Anything else is too complicated for (my) practical use. That's for B&W (and color slides purchased several bricks with the same emulsion number). For color negative I just use one stop more exposure than rated ISO.
-- Bill Mitchell (firstname.lastname@example.org), February 19, 2002.
Actually, I think Tim is right about having to factor in the flare...
-- Russell Brooks (email@example.com), February 20, 2002.
I would imagine if you have access to a densitometer, it's easy. Otherwise, generally follow Fred Picker's advise (and others who have similar methods). Basically, focus on a grey card, make sure the light is even, meter normally, Then stop down 5 stops (or get to five stops down). Shoot. Then put the cap on. Shoot. I then take the cap off, and shoot again. But it's variations on this; some advise opening up also, to get to zone X. I guess you can. It's a good thing to do, because once you have found your N, you can forget about that part of the process. You should also look at N-1, N-2, N+1 and N+2.
Or, i imagine, you can find some standard scene, and see if different films, EIs, development times yield similar negs. I use the hallway outside my apartment at night, so there's no light coming in from the window at the end of the hall, only interior lighting.
-- Ronald Gans (firstname.lastname@example.org), March 11, 2002.
Regarding determining EI with large format negatives:
I found this site (sorry, URL has long since been lost) which described a great way to determine EI and save film at the same time.
Take a thin piece of cardboard (I used mat board) and cut it so it fits inside the frame of your film holder. Then, cut a series of rectangular openings. On a 4x5 negative, I cut out three rows of five. Three rows of four are probably better. Save the cutouts. Then, take some thinner cardboard (the cardboard inside film packages works great) and cut them into rectangles that are just a bit bigger than the first set of cutouts. Glue the thinner pieces onto the smaller pieces.
You'll probably want to mark the original cutouts so you know which hole they go back into. Orientation is important as well for a good fit.
Once you've created the 'plugs', here's what you do:
1. Tape the card board cutout into the opening of your film holder. You'll have to load film first :-) Keep the dark slide in place.
2. Point your camera at an evenly lit wall, and take the camera slightly out of focus. You don't want detail.
2. Set your film speed for 1/2 the recommended ISO, and meter the wall. Close down by four stops to get a zone I exposure. Then, remove the first plug, remove the dark slide, and make the exposure. Replace the plug and dark slide.
3. Now increase the film speed by 1/3 of a stop by closing down the iris. Repeat with plug #2. Do this until you've used 7 plugs. So, if you're testing 400 ISO film, this will give you exposures at 200, 250, 320, 400, 500, 600 and 800.
4. Going back to the original metered (zone V) exposure at EI 200, close down the iris (or change the exposure time) 3 stops. This will be a zone VIII exposure. Follow the above sequence again, closing down by 1/3 of a stop for each of the remaining squares.
5. Develop the negative as per the manufacturers instructions.
6. Using a densitometer, read the squares. Find the square in the first sequence that is 0.10 over film base+fog. This is your correct zone I exposure, and determines your EI.
7. Now look at the second set of squares, and find the one that has the same EI as the first set. Read this square.
If you're using a condenser enlarger, you want the net densitiy to be between 1.15, and 1.25. If you're using a diffusion enlarger, the range is 1.25 to 1.35. Alter your development time to get the densties somewhere in this range.
The cardboard cutout can be used for testing all your film/developer combinations, as well as n+/-? development times. It saves film, and times during the whole process.
This is pretty much the same sequence that Ansel Adams describes in his book The Negative; it's just a bit more frugal with film.
Hope that helps and LF photographers out there who want to do testing!
The same applies to roll-film users as well; you just don't need the cardboard cutout, plugs and dark slide :-)
-- Ken Miller (email@example.com), March 11, 2002.